Switching devices



1968 n. WHEABLE ETAL 3,419,731

SWITCHING DEVICES Filed Jan. 4. 1966 sheet I of 5 FIG.I

3 8 o. WHEABLE ETAL 3,419,731

SWITCHINGDEV'ICES Filed Jan. 4. 1966 Sheet 2 of :5

TAPE 34 RFADER UNE mo BANK PL United States Patent 3,419,731 SWITCHINGDEVICES Desmond Wheable, Camberley, and Edward B. Stuttard,

Wheathampstead, England, assignors to Hawker Siddeley Dynamics Limited,Hatfield, England, a company of Great Britain Filed Jan. 4, 1966, Ser.No. 518,722 Claims priority, applicatiorg/(grseat Britain, Jan. 5, 1965,

42 9 Claims. (Cl. 307-415) This invention relates to improved switchingdevices, and apparatus formed therefrom.

According to the present invention, a switching device comprises aplurality of reed switches angularly dispo sed about an axis and eachoperable by means of a imagnetic field to assume either one of a firstand a second condition, means associated with each switch to hold theassociated switch in the second condition when so operated, and anelectromagnet having an armature rotatable about said axis in proximityto said switches and energisable to change the condition of any one reedswitch in proximity thereto.

According to one specific embodiment of the invention, there is provideda switching device comprising a plurality of reed switches angularlydisposed about and extending radially of an axis and each operable bymeans of a magnetic field to assume either one of an open and closedcondition, a separate permanent magnet associated with each switch tohold the associated switch in the closed condition when so operated, andan electromagnet having a fixed coil and an armature rotatable aboutsaid axis in proximity to said switches and energisable to change thecondition of any one reed switch in proximity thereto.

The invention also extends to a switching device according to either ofthe two immediately preceding paragraphs in combination with means forapplying to the electromagnet, in synchronism with the rotation of thearmature, energising pulses to change the conditions of the switches.

The term reed switch is used herein to denote a switch comprising atleast two electrical contacts disposed within an envelope and operablebetween a first and a second condition by means of an applied magneticfield. The envelope may be evacuated, or may contain a gas inert to thematerial of the contacts, for example, nitrogen.

According to one aspect of the invention, there is provided anelectrical selector formed from switching devices according to theinvention, the electrical selector comprising first electrical pulsingmeans for selectively closing any one of at least two of the reedswitches of a primary switching device according to the invention andthereby selecting an electrical connection to a corresponding one of atleast two secondary switching devices each according to the invention,and second electrical pulsing means, operable through said selectedelectrical connection, for selectively closing any one of at least twoof the reed switches of the secondary switching device and therebymaking a required electrical connection.

According to a specific embodiment of this one aspect of the invention,there is provided an electrical selector comprising a primary swtichingdevice according to the invention operable by an electromagnet andhaving at least two of its reed switches respectively connected to theelectromagnets of a corresponding number of secondary switching deviceseach according to the invention, all of the switching devices havingtheir armatures arranged for synchronous angular rotation, firstelectrical pulsing means operable upon the electromagnet of the primaryswitching device at a first angular position of the armature to closeone of the reed switches of the 3,419,731 Patented Dec. 31, 1968 "iceprimary switching device and thereby select an electrical connection tothe electromagnet of the corresponding one of the secondary switchingdevices, and second electrical pulsing means operable through saidselected electrical connection upon the electromagnet of the selectedsecondary switching device at a second angular position of the armatureto close one of the reed switches of the selected secondary switchingdevice and thereby make a required electrical connection.

The electrical selector of the two immediately preceding paragraphs mayinclude neutralising means, for example at least one constant-currentgenerator, arranged to be capable of passing an electric current throughthe electromagnet of the primary switching device, and/or through theelectromagnets of the secondary switching devices, in a relativelyopposite direction to the first and second electrical pulsing meansrespectively, so as to restore at least one of the reed switches of therelevant switching device to the open condition.

According to a second aspect of the invention, there is provided adiscontinuously variable resistor formed from a switching deviceaccording to the invention, the discontinuously variable resistorcomprising a switching device according to the invention and an array ofat least two fixed-value resistors each of which has one of itsterminals connected to a corresponding one of the reed switches of theswitching devices.

According to a specific embodiment of the second aspect of theinvention, a discontinuously variable resistor com-prises a switchingdevice according to the invention and at least two arrays of fixed-valueresistors, each array of fixed-value resistors including a plurality ofsuch resistors arranged in graduated order of resistance and eachrespectively and uniquely associated with a corresponding one of thereed switches of the switching device, each of the fixedlvalue resistorsof each array having one of its terminals connected to a first commonpoint of that array and having the other one of its terminals connectedto one terminal of the corresponding reed switch, the other terminals ofthe reed switches associated with each array of fixed-value resistorsbeing connected to a second common point of that array, and the first orthe second common points of each array being so connected to the firstor the second common points of the next array, that operation of theswitching device permits any fixed-value resistor of one array to beconnected in series with any one fixed-value resistor of the next array.

The invention also extends to a digital-to-analogue converter whichincludes electrical pulsing means for operating the switching device ofa discontinuously variable resistor according to either one of the twoimmediately preceding paragraphs at at least one angular position of itsarmature and according to preselected information in digital form, thefixed-value resistors being so chosen that their effective resistancerepresent in analogue form the preselected information in digital form.

Furthermore, the invention also extends to a generator of astaircase-type waveform, the generator including a discontinuouslyvariable resistor according to the invention, means for temporarilyclosing each of the reed switches of the switching device in a suitablesequence, and means for passing an electrical current through thediscontinuously variable resistor, whereby the potential differencedeveloped across the discontinuously variable resistor is of therequired form.

Several embodiments of the invention will now be described by way ofexample, reference being made to the accompanying drawings in which:

FIGURE 1 is a fragmentary sectional view of a switching device accordingto the invention;

FIGURE 2 is a sectional view taken along the line II-II of FIGURE 1,with parts omitted;

FIGURE 3 is a circuit diagram of an electrical selector according to theinvention, and

FIGURE 4 is a circuit diagram of a discontinuously variable resistoraccording to the invention.

Referring to FIGURES l and 2, the switching device includes a pluralityof reed switches 1, for example thirtytwo in number, disposedequiangularly about and extending radially of an axis 2. Each switch 1is an ON-OFF switch having two normally open contacts 3 and 4 within anenvelope 5, the contacts being operable to the closed condition by anapplied magnetic field. The switches 1 are carried upon a ring-shapedboard 6 which conveniently also carries a number of printed-circuitelements.

Separate means is associated with each switch 1 to hold that switch inthe closed condition when it has been caused to assume that condition byan applied magnetic field. In this example, such means is a permanentmagnet 7 retained in a corresponding slot in the board 6.

In a modification of the invention (not illustrated), each switch 1 is achangeover switch having two side con tacts and one changeover contact.The arrangement is then such that, in a first condition of the switch 1,the changeover contact touches one of the side contacts; upon theapplication of an applied magnetic field, the changeover contact changesover, to touch the other of the side contacts, the switch 1 being heldin this second condition by means such as a permanent magnet 7.

A shaft 8 is provided concentrically with the axis 2 for rotation aboutthat axis and carries for rotation therewith the armature of anelectromagnet the coil 9 of which is stationary, being arranged withinthe central aperture of the board 6.

The armature includes two radially extending arms 16 and 11 disposed oneon either side of the board 6 and having respective pole faces 12 and 13so disposed relatively to the switches 1 as to close or open thatparticular switch 1 which is disposed between the arms and 11 when thecoil 9 is energised by an electrical pulse appropriate to the conditionwhich it is desired to cause that switch to assume.

The magnetic circuit of the armature is completed by a sleeve 14 formingone end of the arm 11, the sleeve 14 being arranged to coaxiallysurround the shaft 8, and to extend through the coil 9 to the arm 10.

In the operation of the device, the shaft 8 with the arms 10 and 11 andthe sleeve 14 is rotated. At appropriate instants in time, when anygiven one of the switches 1 is required to be operated and lies betweenthe arms 10 and 11, an electrical pulse of appropriate polarity isapplied to the coil 9 so as to produce, between the pole faces 12 13, aresultant magnetic field sufiicient to close the contacts 3 and 4 ofthat switch 1. When the electrical pulse has ended, the magnet 7associated with that switch 1 will retain that switch in the closedcondition.

Similarly, any one of the switches 1 which is in the closed conditionmay be caused to assume the open condition by energising the coil 9 witha pulse of relatively opposite porality, when that particular switchlies between the arms 10 and 11, the magnetic field so generated beingsufiiciently strong to overcome the elfect of the associated magnet 7.

If desired, two or more switching devices may be axially spaced along ashaft 8 common to all of the devices, so that the a-rmatures of thedevices can be rotated in synchronism. Magnetic screens 15 may belocated between adjacent switching devices, to localise the magneticfields associated with each device.

The switches 1 need not extend radially of the axis 2 as described, butmay extend parallel to that axis. Thus, the switches 1 of one or moreswitching devices may be carried on the wall of a cylinder coaxial withthe axis 2.

It will be appreciated that the switching device described may beoperated by applying electrical energising pulses to the coil 9 insynchronism with rotation of the shaft 2 to operate the switches it in aselected sequence or in a predetermined pattern.

Referring to FIGURE 3, the electrical selector there shown includes anarray of switching devices of the type provided according to theinvention, these switching devices being arranged upon, and axiallyspaced along, a shaft (not shown) similar to the shaft 8, whereby thearmatures (not shown) of all of the switching devices can -be rotated insynchronism and in phase.

Of the array of switching devices, a first one, the primary switchingdevice, is indicated at 21, its electromagnet coil being indicated at22. The switching device 21 has one contact of each of its thirty-tworeed switches connected to a common point 23, the other contacts of thereed switches being indicated at 24: because of this, the operation ofthe switching device is similar to that of a single-pole thirty-two-wayrotary switch, and the switching device 21 is symbolically indicated assuch in FIGURE 3. The array of switching devices also includesthirty-two secondary switching devices 25 each having its reedswitchcontacts connected similarly to those of the switching device 21, andeach therefore similarly symbolically indicated.

Each of the non-commoned contacts 24 of the primary switching device isconnected to one terminal of the electromagnet coil 26 of acorresponding one of the secondary switching devices 25, each of theseelectromagnetic coil terminals being also similarly connected, by way ofa corresponding rectifier 27 of the polarity indicated, to one terminalof a constant-current generator 28 the other terminal of which isconnected to a zero terminal 29. The remaining terminals of theelectromagnet coils 26 are all connected to a common line terminal 30and are also all connected to earth, via a rectifier 49 of the polarityindicated.

The electrical selector also includes an auxiliary switching mechanismindicated at 31. This mechanism is generally similar in form to theswitching devices according to the invention, but differs in that thepermanent magnet 7 associated with the reed switches are omitted;furthermore, the electromagnet coil 9 is replaced by a permanent magnet.During operation of the auxiliary switching mechanism, its armaturerotates in synchronism and in phase with the arinatures of the array ofswitching devices, all of the armatures being mounted upon the commonshaft referred to above; it will be clear that, in this case, each ofthe reed switches of the auxiliary switching mechanism will betemporarily operated to the closed condition in se quence and during theperiods when the pole-faces of the armature of the mechanism sweep pastthe reed switch in question. The thirty-two reed switches of theauxiliary switching mechanism have each one contact connected to acommon point 32; the remaining contacts of the reed switches areindicated at 33, and are respectively connected to thirty-two selectionterminals 34. The common point 32 is connected to the input of adirect-current amplifier 3-5 the output of which is connected, by way ofa rectifier 36 of the polarity indicated, to a common point 37 which isconnected, on the one hand, to the common point 23 and, on the otherhand, by way of a rectifier 38 of the polarity indicated, to a commonpoint 39. The common point 39 is connected to one terminal of aconstant-current generator 40 the other terminal of which is connectedto earth, and is also connected, by way of the electromagnet coil 22, toa bank terminal 41.

In the case of each of the secondary switching devices 25, each havingthirty-two reed switches, one contact of each of the reed switches isconnected to a common point 42. The remaining contacts 43 can beindividually connected to any desired electrical circuit or circuits towhich electrical connections are required to be made by means of theelectrical selector.

The electrical selector being described is designed to be employed tooperate certain ones or groups of the reed switches of the secondaryswitching devices in sequences, according to instructions pre-recordedupon tape which, when it has been suitably coded, is fed into a tapereader 44. This part of the apparatus forms no part of the invention;briefly, however, each instruction character upon the tape comprises apermutation based upon the perforation or non-perforation of the tapeinto holes at eight positions spaced laterally of the tape. The state ofthe first five of these hole-positions, giving thirty-two permutations,is detected by the tape reader 44 and, according to a prearranged codeand by means of known apparatus (not shown), an electrical connection ismade to a predetermined one of the thirty-two section terminals 34,making that contact live, this electrical connection being to thepositive terminal of a direct-current source (not shown) the otherterminal of which is connected to earth. Two of the remaininghole-positions are similarly tested by the tape reader 44 and, accordingto a pre-arranged code and by means of known apparatus (not shown), oneof three types of electrical connection is arranged to be made; either(i) the bank terminal 41 is connected to earth, or (ii) the lineterminal 30 is connected to earth, or (iii) both the line terminal 30and the zero terminal 29 are connected to earth. The remaininghole-position upon the tape is employed for checking purposes.

The operation of the electrical selector of FIGURE 3 will now bedescribed, supposing that all of the reed switches of the primary andsecondary switching devices 21 and 25 are initially in the opencondition, and that the common shaft of the switching devices 21 and 25and the switching mechanism 31 is rotated continuously by a motor (notshown).

Suppose that it is required to first close the second reed switch of thefirst of the secondary switching devices, and then to close the secondreed switch of the thirty-second and last of the secondary switchingdevices. Four information characters upon the tape will be required forthis sequence: thus, the first information character is employed tochoose the first of the thirty-two secondary switching devices, thesecond information character to choose the second reed switch of thatdevice, the third character to choose the last of the secondaryswitching devices, and the fourth character to choose the second reedswitch of that device.

Thus, when the first information character is read, the first of theterminals 34 will be automatically made live as described above; inaddition, the bank terminal 41 will be automatically earthed.Consequently, as the armature of the auxiliary switching mechanism 31rotates, firstly, the constant-current generator 40 will cause a cnstantcurrent to flow, in the direction indicated by the arrow 45, through theelectromagnet coil 22, the direction and magnitude of this current beingarranged to be such that the reed switches of the primary switchingdevice 21 are restored to the open condition; secondly, when,simultaneously, the first reed switches of both the switching mechanism31 and the switching device 21 are embraced by their respectivearmatures, an electric current will fiow from the first selectionterminal 34 to the input of the amplifier 35, resulting in an electricalcurrent pulse flowing from the output of the amplifier 35 to the commonpoint 37 and thence via the common point 39 and through theelectromagnet coil 22 in the direction of the arrow 46, to earth at thebank terminal 41, this current being arranged to be sufiicient toovercome the constant current flowing oppositely through the coil 22 andto cause the electromagnet to operate the first of the reed switches ofthe primary switching device to the closed condition; this creates asemi-permanent circuit connection between the common point 23 and theelectromagnet coil of the first (left-hand-end in FIGURE 3) secondaryswitching device.

This operation being complete, the tape reader 44 is directed to readthe second information character which will be such that the second ofthe terminals 34 will now be made live as described above and, inaddition, the

line terminal 30 will be connected to earth. As all of the armatures(not shown) rotate in phase, an instant will occur when they all embracethe second reed switch of the relevent switching device, 21 or 25, orswitching mechanism 31. At this instant, as before, an electric currentwill flow from the second of the terminals 34 and will again result inan electrical current pulse flowing from the amplifier 35 to the commonpoint 37; thence, this current fiows, via the semi-permament circuitconnection described above, to the electromagnet coil 26 of the firstsecondary switching device, and then to the earthed line terminal 30.This current is arranged to flow in the direction of the arrow 47through the electromagnet coil concerned, so as to operate the second ofthe reed switches of the first secondary switching device. A furthersemipermanent circuit connection is thus established within thatsecondary switching device.

This operation completed, the tape reader 44 is then directed to readthe third information character which will be such that the last of theterminals 34 will be made live as described above, and, in addition, thebank terminal 41 will be earthed. The further operation of thearrangement will now be clear, it being only remarked that thesemi-permanent circuit connection previously created within the primaryswitching device 21 will be automatically removed by the action of theconstant current from the generator 40, and replaced by a differentsemi-permanent circuit connection within that switching device.

In the manner described, then, any required number of the total of 32times 32 reed switches of the secondary switching devices can beoperated to the closed condition in sequence, each operation requiringtwo information characters and a minimum of two rotations of the commonshaft of the armatures.

All of these reed switches can thereafter be restored together to theiropen condition, if the tape reader is arranged to read an informationcharacter which is such that the zero terminal 29 is connected to earth.In this case, the constant-current generator 28 causes current to flow,in the direction of the arrow 48, through all of the parallel-connectedelectromagnet coils 26, by way of the rectifiers 27, the terminal 29 andthe rectifier 49, this current being arranged to be sufficient to causethe electromagnets to restore all of the reed switches of the secondaryswitching devices to their open conditions in sequence, as the armaturesof those devices rotate.

Thereafter, the tape reader 44 may be arranged to cause another one, oranother group, of the reed switches of the secondary switching devicesto be operated to their closed conditions.

It is to be understood that the primary and the secondary switchingdevices, 21 and 25, and the auxiliary switching mechanism 31, need nothave thirty-two reed switches each, but may have any other suitablenumber. Furthermore, it is to be understood that the reed switches ofeach of the secondary switching devices 25 need not have common points42 as shown in FIGURE 3, but may, if preferred, be employed asindividual switches which are not interconnected.

Referring to FIGURE 4, the discontinuously variable resistor there shownis formed from a switching device according to the invention, andemploys thirty of the thirty-two reed switches of the switching devicedescribed with reference to FIGURES 1 and 2. In the case of the firstten reed switches, one contact of each reed switch is connected to acommon point 60 so that the arrangement can be represented, similarly tothe case of FIGURE 3, as a single-pole ten-way rotary switch, while, ofthe remaining contacts of the reed switches, that of the first isdirectly connected to a common point 61 to which the remainder, each viaan appropriate corresponding one of an array of fixed-value resistors 62in graduated order of resistance, are also connected.

The next ten reed switches are similarly connected, one

contact of each reed switch being connected to a common point 63 and, ofthe remaining contacts, the last one is directly connected to a commonpoint 64 to which the remainder, each via an appropriate correspondingone of an array of fixed-value resistors 65 in graduated order ofresistance, are also connected.

Finally, the last ten reed switches have one contact of each reed switchconnected to a common point 66 and, of the remaining contacts, the firstone is directly connected to a common point 67 to which the remainder,each via an appropriate one of an array of fixed-value resistors 68 ingraduated order of resistance, are also connected.

The common points 60 and 64 are connected together, as are thecommonpoints 63 and 67. The common points 61 and 66 are respectivelyconnected to the output terminals 69 and 70 of the device, andaconstant-current generator 71 has one of its terminals connected to thecommon point 61 and the other terminal connected, via a fixed resistor72, to the common point 66.

The resistors 62 have resistances which range, as indicated in FIGURE 4,from 0.1 to 0.9 of a preselected resistance R, by intervals of 0.1 R.The resistors 65 have resistances which range from 0.09 R to 0.01 R, byintervals of 0.01 R. The resistors 68 have resistances which range from0.001 R to 0.009 R, by intervals of 0.001 R.

It will thus be appreciated that, if the switching device is so operatedthat, at any one time, not more than one of the ten reed switches ofeach series of then is operated, then the device will behaveessentially, as regards the total resistance presented between thecommon points 61 and 66, as a three-decade resistance box capable ofpresenting any required resistance from zero to 0.999 R, with aresolution of one part in a thousand. Due to the presence of theconstant-current generator 71, the potential difference presentedbetween the output terminals 69 and 70 will vary in proportion to thetotal resistance presented between the terminals 61 and 66.

Such a device can be employed as a cligital-to-analogue converter. Thusif a digital code is arranged to cause operation to the closed conditionof a trio of reed switches of the switching device, one reed switchbeing selected from each of the three decades according to the digitalinformation, then the potential difference appearing between the outputterminals 69 and 70 will represent the digital information in analogueform. In particular, the present device may form one of the secondaryswitching devices 25 described with reference to FIGURE 3, theelectrical selector there described serving to supply the requisitedigital information; however, any other suitable electrical pulsingmeans may be employed to operate the switching device of thedigital-to-analogue converter.

The device described with reference to FIGURE 4 can also be arranged toact as a generator of a staircase-type waveform. It will be basicallyclear that the potential difference appearing between the outputterminals 69 and 70 will vary step-wise, if the connections made to theresistors 62, 65 and 68 by the reed switches are varied stepwise. Toobtain a staircase-type waveform at the terminals 69 and 70, thewaveform consisting of ascending and/r descending steps of potentialdifference, all that is required is suitable means for temporarilyclosing the reed switches of the switching device concerned in asuitable sequence; such means may be an electrical selector of thegeneral form described with reference to FIG- URE 3, but may have anyother suitable form. If, for example, the device of FIGURE 4, commences,as shown, with the first, eleventh and twenty-first reed switchesclosed, and if the first reed switch is opened and thereafter the secondto the tenth reed switches are first closed and then opened in sequence,then it will be seen that the total resistance presented between thecommon points 61 and 66 will vary, in steps of 0.1 R, from 0.09 R to0.99 R, causing a corresponding staircase-type waveform to appearbetween the output terminals 69 and 70.

We claim:

1. A switching device comprising a plurality of reed switches angularlydisposed about an axis and each operable by means of a magnetic field toassume either one of a first and second condition, means associated witheach switch to hold the associated switch in the second condition whenso operated, and an electromagnet having an armature rotatable aboutsaid axis in proximity to said reed switches and energisable to changethe condition of any one reed switch in proximity thereto.

2. A switching device according to claim 1 wherein said reed switchesextend radially of said axis.

3. A switching device according to claim 1 wherein said means forholding the associated switch in said second condition comprises apermanent magnet.

4. A switching device according to claim 3 including means for applyingto the electromagnet, in synchronism with the rotation of the armature,energizing pulses to change the conditions of the switches.

5. A switching device according to claim 3 wherein the armaturecomprises two radially extending arms having respective pole faces sodisposed relatively to the switches as to close or open that switchwhich is disposed between the pole faces when the coil of theelectromagnet is energised by an electrical pulse appropriate to thecondition which the switch is to be caused to assume.

6. A switching device according to claim 5 wherein the magnetic circuitof the armature is completed by a sleeve forming one end of one of thetwo arms and arranged coaxially around a shaft coaxial with said axis,said sleeve extending through the coil of the electromagnet to the otherof said two arms.

'7. A discontinuously variable resistor comprising a switching deviceaccording to claim 3 and an array of at least two fixed-value resistorseach of which has one of its terminals connected to a corresponding oneof the reed switches of the switching device.

8. A discontinuously variableresistor comprising a switching deviceaccording to claim 1 and at least two arrays of fixed-value resistors,each array of fixed-value resistors including a plurality of suchresistors arranged in graduated order of resistance and eachrespectively and uniquely associated with a corresponding one of thereed switches of the switching device, each of the fixedvalue resistorsof each array having one of its terminals connected to a first commonpoint of that array and having the other one of its terminals connectedto one terminal of the corresponding reed switches, the other terminalsconnected to one terminal of the corresponding reed switch, the otherterminals of the reed switches associated with each array of fixed-valueresistors being connected to a second common point of each array beingso connected to the first or the second common points of the next array,that operation of the switching device permits any fixed-value resistorof one array to be connected in series with any one fixed-value resistorof the next array.

9. A switching device according to claim 1 wherein said electromagnethas a fixed coil.

References Cited UNITED STATES PATENTS 3,038,976 6/1962 Koda 335-454 X3,053,951 9/1962 Poinsot et a1 335154 X 3,056,868 10/1962 Jacobson etal. 335l54 X 3,359,463 12/1967 Jones 335152 X ROBERT K. SCHAEFER,Primary Examiner.

T. B. IOIKE, Assistant Exal'niner.

US. Cl. X.R.

1. A SWITCHING DEVICE COMPRISING A PLURALITY OF REED SWITCHES ANGULARLYDISPOSED ABOUT AN AXIS AND EACH OPERABLE BY MEANS OF A MAGNETIC FIELD TOASSUME EITHER ONE OF A FIRST AND SECOND CONDITION, MEANS ASSOCIATED WITHEACH SWITCH TO HOLD THE ASSOCIATED SWITCH IN THE SECOND CONDITION WHENSO OPERATED, AND AN ELECTROMAGNET HAVING AN ARMATURE ROTATABLE ABOUTSAID AXIS IN PROXIMITY TO SAID REED SWITCHES AND ENERGISABLE TO CHANGETHE CONDITION OF ANY ONE REED SWITCH IN PROXIMITY THERETO.